I smell a rat
by ThalyaWonders
Summary: An experiment, a mystery and something unusual. One-shot about Sherlock. Pre-series, pre-John, pre-221B Baker Street. I should mention that Sherlock does already know Molly and Lestrade.


**Author's Note: My first one-shot, I hope you enjoy!**

* * *

I SMELL A RAT

Sherlock is right in the middle of preparing his latest experiment. Molly gave him permission to use the ears of five bodies in the morgue, meaning he now has five sets of ears that he can use to determine the different effects of different poisons on cartilage. After doing a few standard tests he writes a couple notes down for each set of ears. Most important is the cartilage to flesh ratio and the suppleness of the cartilage. It's when he's thinking of the perfect way to execute his experiment, that he is distracted.

At first, the sound is faint. Or maybe Sherlock is just too occupied with his experiment to properly register it. Over the course of the next ten minutes, the sound becomes harder to ignore. When finally, after persisting another ten minutes the sound becomes unbearable, Sherlock snaps. He gets up and paces towards the door. When swinging open the front door violently, he's ready to give the person on the other side a lecture about the importance of knowing the effects of poison on cartilage, and the gravity of interrupting him during a very important phase of his experiment. When the door is fully open however, no one is there. After a second of confusion, Sherlock's senses kick into action.

Looking around in the hallway he sees nothing that could point to the recent presence of anyone, or anything in front of his door. He scolds himself for having cleaned the hallway last week. The dust could've helped him determine who or what had been at his door, but now he has nothing to go on. He inhales deeply through his nose. No suspicious smells. He stands still, slows down his breath and heartbeat, and listens. After a minute he hasn't heard anything of importance. He turns around and walks back into his flat. He locks the door.

His mind now occupied with the mystery of the invisible disturber, he settles himself on the couch, hands pressed together under his chin. He goes into his mind palace. He plays the sound he heard again, and compares it to the sound database he has in his mind. None of the sounds in the categories to which the sound he heard could belong are a match. He can't deduce what made the sound, and it irritates him endlessly.

Sherlock must have fallen asleep sometime during his brainstorming, because he suddenly awakes with a start. After registering it's between ten and eleven in the evening, using the position of the moon which he can see through the window, he sits up slowly. As he looks around in his flat, he notices a couple of things. Firstly, there is a sheet of music lying on the ground, that was certainly not there before. Couldn't have been caused by a draught, because all his windows are closed. And secondly, someone has knocked over the glass of water that stood on the countertop. Someone must be inside his flat.

Without a sound Sherlock gets up and walks over to his front door. He tries to open it, but it's still locked. He turns around and walks towards the window. He looks at the windowsill. The dust is not disturbed, so whoever is inside, didn't enter through the window. Sherlock's face contorts into a frown. All these different observations, they don't fit, they don't make sense.

He has two theories concerning the locked door. One: Someone picked the lock, came in and then locked the door again. Very unlikely. Why disable your own escape route? Two: Someone was already inside. Also very unlikely. I haven't had visitors over for over four weeks and this afternoon there was no one who could've gone inside. Unless they were invisible. As this is scientifically impossible, he can exclude this option. He can't discard the second theory completely, as he doesn't have enough evidence to deduce what precisely _did_ happen.

The sheet of paper he can explain. If someone walked past it, the flow of air could've caused the paper to fall to the ground.

The glass of water confuses him. It's almost impossible that it was knocked over by accident. Its place and the way it fell down all point towards the fact that it was knocked over purposely. But why? To scare him? It's what woke him up, was that the incentive?

He puts his hands under his chin again and starts working on a theory that makes sense. Only a couple of minutes have passed, when he hears it. The sound, the same sound he had heard earlier. But this time, it's not coming from the front door. It's coming from his bedroom door. Only now he notices that his bedroom door is shut. It wasn't when he went into his mind palace. He makes a mental note that he should pay more attention from now on, he has started slacking off a bit when it comes to observations.

Slowly, he walks over to his bedroom door. When walking past the kitchen area of his flat, he doesn't think to stop and grab something he can defend himself with, his mind is racing, trying to figure out what is behind the door.

When he stands in front of the door, the sound stops. Presumably whatever is behind the door, heard him and knows he is there, knows he might open the door any second now. Which means the person on the other side will be expecting it. Sherlock no longer has the advantage of the element of surprise.

Considering this, he still decides to open the door. He has to know what's on the other side, what has managed to escape his brilliant mind so far. He turns the door handle, and opens the door only slightly, when something is catapulted out of his room. Sherlock only sees a dark blur, before it's gone.

Quickly, he turns around, trying to get a visual on the creature, but he's too slow. The only thing he can see is his flat, the same as it was since he woke up. Annoyed with the fact that something is toying with him, he sets on searching the whole flat, but after returning to his couch, this turns out to be unnecessary.

Perched on one of the chairs, is a cat. A beautiful black cat, with a tiny spot of white right behind her left ear. Lying completely at ease. Purring, even, if his ears don't deceive him. Sherlock's mind goes blank for a second. Then his neurons start transmitting signals again, and everything makes sense.

The sound he heard was the cat, scratching at his door. The cat must have entered his flat, when he opened the door. He was looking at eyelevel, not down, that's why he didn't see it. It also explains the sheet of music and of course, the glass of water.

Sherlock looks back at to the cat. Now what? He can't keep a cat. He decides to just show it out. Carefully he lifts the cat with one hand. The softness of the fur against his skin surprises him. He can't remember the last time when he pet a cat. With a little shrug, he walks over to the front door, unlocks it, and puts the cat down, outside of his flat. A soft meow escapes from the cat.

The next day when he goes out to get some more compounds for his experiment, he looks around when he steps out the front door. The cat is gone. What he does see, are some scratches in the left side corner on the bottom of the door.

When Sherlock returns, the cat is back. Its green eyes fixed on him. It's sitting in a corner, like it has been waiting for him. Sherlock looks away after a couple of seconds. As he unlocks his front door, the cat doesn't show any indications that it wants to come inside.

When Sherlock starts to feel faint at two a.m. he remembers that he hasn't eaten for over two weeks. First there was a case, so he couldn't eat, and now he's doing an experiment, so he shouldn't be eating. He needs the full capacity of his brain. A couple of minutes later however, Sherlock realises that it would be more effective to eat, since he's on the verge of fainting.

While grabbing a biscuit, his mind wanders to the cat outside. It wasn't very well-fed. He had suspected this when he saw the cat, but when he lifted it, his presumption turned out be correct. The cat didn't weigh much. A street cat, obviously. Suddenly Sherlock found himself wondering if he should give the cat some food. The weather is still quite harsh and without enough food the cat might not be able to keep itself warm. But then he's finished his biscuit and his mind returns to the experiment.

A couple of days later Sherlock has to go outside his flat again. This time, the cat is already there. When he steps outside, it walks over to him. It rubs his head against his right leg. Amazed by the strange feeling, Sherlock stops for a second. He looks down. The cat stops, sits down and looks up. Green eyes meet icy blue ones. Sherlock blinks and the cat looks away.

On the way to the shop he is replaying the moment. Why did he get the feeling that the cat was intelligent when it looked at him? He shakes his head and keeps walking.

Returning with a bag full of dangerous chemicals, he finds the cat waiting for him again. Secretly, he is a tiny bit happy. When he's put the bags away, he returns outside with a little bowl. 'Look at what I've brought you.' He says to the cat, before he even realises it. When he puts the bowl down, the cat starts drinking the milk immediately. Sherlock's frown disappears and he goes back inside.

When adding the two different chemicals he's holding, he expected to hear a soft fizzing sound. Instead he hears something else. A soft meow comes from his front door. He sighs. After putting down the beaker that he was using, he gets up and opens the door, placing his foot in such a way, that the cat can't enter. 'No, you can't come in, I'm busy.' With that he closes the door and the meowing stops. He returns to his experiment, almost completely forgetting about the cat.

A few days later Sherlock had gone to the morgue. He had asked Molly if she had any dead animals, or alive for that matter. He had gotten a new idea for a future experiment, after he had found a hairball on his doorstep. Molly had reacted angrily and ushered him out of the morgue, telling him to come back when he was able to be more like a normal person.

When arriving at his flat, he finds himself looking for the cat. When he sees it, he's relieved. As if sensing his mood, the cat walks towards him and rubs its head against his leg again. 'Alright, alright.' Sherlock mutters, trying to find his key. As he's opening the door, the cat walks over to it, obviously wanting to go back in. After a little moment, Sherlock decides that he sees no reason why he shouldn't let it in. His experiment about cartilage is almost done, and without a case, he will only be bored.

He opens the door and steps inside, then turns around. He makes a gesture with his hand, as to say: come on in. The cat looks at him and follows him inside. Trotting lightly on its paws, the cat starts to walk through the flat, exploring it. After half an hour Sherlock decides to check up on it, only to find it lying on the exact same chair as almost a week ago. With a slight smile he returns his attention to his experiment.

A day has passed and Sherlock has finally finished his experiment. The effect of different poisons on cartilage post-mortem were minimal. He will have to try it on a live specimen. A soft meow enters his ear and he remembers that he should probably give the cat some food. Looking through a cabinet, he finds a can of tuna. That will do for now, but he has to go and buy some real cat food soon. Just when he's about to look up the best cat food you can buy, he hears a knock on the door. 'Busy!' He shouts, hoping that whoever is out there will leave. But the voice that responds is a familiar one. 'Open up Sherlock, come on.' It's Lestrade.

Sherlock jumps up, the idea of a case filling him with happiness. This sudden movement scares the cat, which flees to his bedroom.

Sherlock opens the door and his good feeling is gone. Behind Lestrade are Sally Donovan, Philip Anderson and a bunch of other people. 'What are you doing here?' Sherlock asks, already knowing the answer. 'It's a drugs bust.' Anderson replies from the back, which earns him an angry glare from Lestrade. 'We just want to make sure you don't fall of the wagon.' Lestrade says, without looking him in the eye. 'No, there's more.' Sherlock says, while looking at Lestrade, deducing all sorts of information. 'Why are you really here? Why did you come now? You haven't seen me for over six weeks, why would you think anything was wrong?' Meanwhile, people are walking into his flat.

'Molly.' Lestrade replies, finally looking at him. 'What about Molly?' Sherlock asks, confused as to how she is of importance. Lestrade sighs. 'Molly told me you acted strange the other day. The day you went to the morgue.'

Sherlock is about to reply when Anderson suddenly sneezes. He's standing next to the kitchen table, where ten ears are still displayed. 'Anderson, if you insist on spreading your germs, keep them away from my experiment!' Sherlock shouts. Anderson turns around, looking insulted. 'Well it's not _my_ fault that you have used some sort of irritant substance.' Anderson sneers back. He sneezes again. 'What? I haven't used an irritant for this experiment. Nor have I used drugs so you can all go home.' Anderson sneezes again. Suddenly a big smile appears on Sherlock's face.

Lestrade looks at him with suspicion. 'What have you done Sherlock, for god's sake.' With a disapproving look in Lestrade's direction, he turns towards Anderson. 'Anderson,' he begins, 'I think you might be allergic to my new… Carpet. What a shame. Better you stay away, wouldn't want you to sacrifice your health in spite of me.' 'Hold on,' Lestrade replies, 'why don't I believe you? This is the same carpet that you have had as long as I know you. What's really going on. What have you done?' While Sherlock is contemplating whether or not he should answer him, he hears a shriek, coming from his bedroom. When he turns around, he sees Sally coming out of the room, clutching her hand. Upon better inspection, he sees a small dribble of blood going down her arm. Sherlock grins.

Sally shouts. 'That psychopath has a cat!' 'A cat?' Lestrade asks, looking quizzically at Sherlock. Sherlock just shrugs, but on the inside he's smiling broader than he has ever smiled in his life.

Right at that moment, the cat walks out of his bedroom as well. Sally sneakily tries to move herself further away from it. 'It's evil,' she says, 'it just attacked me for no reason.' The cat walks over to Sherlock who lifts it up and holds it in his arms. Immediately the cat relaxes and starts purring. 'Oh yes,' Sherlock responds, his voice filled with sarcasm, 'evil…'

Lestrade realises that this drugs bust isn't necessary and he feels that if he wants to prevent a massive conflict from happening, he has to leave. 'Alright everyone,' he says with loud volume, 'I think we can go home.' He's pointing towards the door. Slowly, everyone shuffles out. At last, only Lestrade is left. He looks at Sherlock once more, frowns and shakes his head. As he walks out, Sherlock hears him mutter something that sounds suspiciously like: 'A cat… Who would've thought… The great Sherlock Holmes _and a cat_…'

Smiling, Sherlock closes the door and pets the cat. 'You really proved yourself worthy today, didn't you?' He is rewarded with a soft meow. Sherlock makes up his mind. 'Well, if I'm going to keep you, you need a name. One that suits you.'

After a moment of thinking he says, 'I think I'll call you Sourcey.' He grins. 'It's short for exorcist,' he explains to the cat. When he doesn't get a reaction, he elaborates. 'Because you just helped me cast out some evil demons.' After that, the cat settles in his lap and falls asleep. Petting Sourcey makes Sherlock sleepy as well, and when he rests his head for a second, he falls asleep.

The consulting detective and his cat. A duo that chases criminals and mice and doesn't care what the rest of the world thinks of them. Asleep, both purring with satisfaction.

* * *

**Author's Note: Please let me know what you thought :D**


End file.
